The immediate hours after the crash of Malaysia Airlines Flight 17 brought far more questions than answers.

But one thing was clear: The deaths of nearly 300 people will put new pressure on the White House and European leaders to address the conflict in Ukraine and confront Russian President Vladimir Putin.

President Barack Obama tried on Wednesday — just hours before the plane went down — to get out in front of the chaos in the region by announcing tougher sanctions against Russian entities. But the tragedy shows there is a long way to go.

“Given its continued provocations in Ukraine … I have approved a new set of sanctions on some of Russia’s largest companies and financial institutions,” Obama told reporters Wednesday in a hastily announced press room speech. “Russia must halt the flow of weapons and fighters across the border into Ukraine.”

If Russia or Ukrainian separatists are responsible for the apparent shoot-down, tougher sanctions against Russia are almost certain to be forthcoming from the Obama administration and Europe, analysts said Thursday. European leaders, especially, will have to face their reluctance to deal with potential blowback — including the possibility that Russia will retaliate by restricting or cutting off energy supplies crucial to countries like Germany.

“I think the West has to say, ‘The gloves are coming off,’” former State Department official David Kramer said. “I would think and hope that at a minimum the U.S. and Europe significantly widen their sanctions. That seems to be a minimal step in this to impose sectoral sanctions.”

“It’s pretty likely the rebels did this with Russian weapons. Even the supply of those kinds of high-tech weapons will make it very hard for the U.S. and the Europeans not to roll in with much more stringent economic sanctions on the Russians and much more political isolation,” said Kori Schake, top foreign policy adviser on Sen. John McCain’s 2008 presidential campaign. “Everybody’s going to be mad at the Russians.”

Thursday’s incident led to another round of tough talk from members of Congress urging a tougher line toward Moscow.

“What Putin needs to do is, really he’s got to back off in southeast Ukraine because he’s just unleashing chaos there,” Rep. Peter Welch (D-Vt.) said on MSNBC. If the weapons used to shoot down the airliner were Russian-made or provided, “it’s going to create an immense and legitimate call for very, very rough and coordinated sanctions against Russia,” he added.

It is hard to argue the Obama administration was ignoring the chaotic situation in Eastern Europe — it had just announced a new round of sanctions and again called out Moscow for shipping arms to separatist forces in Ukraine.

Schake said Obama and his aides must be greatly relieved those new financial and trade restrictions — the strongest ones to date over Ukraine — came before the startling news of the Malaysian airliner’s fate pushed the regional crisis back into the headlines. “It makes them look like they were ahead of the game, for the first time,” she said.

Putin reacted to the new sanctions by lumping Obama’s foreign policy together with that of President George W. Bush and saying U.S.-Russian relations were at “a dead end.”

Proponents of more intense sanctions on Russia for fomenting fighting and instability in Ukraine generally agreed that the hold-up on tougher sanctions wasn’t due to the Obama administration’s unwillingness, but to European leaders’ reluctance to deal with potential blowback — especially if Moscow restricted or cut off energy supplies crucial to countries like Germany.

“The Europeans have been the main brake on further sanctions in part because their economies are much more affected by this than the American economy would be by potential retaliatory moves,” Schake said.

With initial reports suggesting the majority of the 298 people on board the 777 were European, officials there could feel prodded to flex more muscle toward Moscow, former Secretary of State Hillary Clinton said Thursday.

“From my perspective — and I have the benefit of not being in the government — if there is evidence linking Russia to this, that should inspire the Europeans to do much more,” Clinton said in an interview taped for broadcast on PBS’s “Charlie Rose Show.”

“So, Europeans have to be the ones to take the lead on this,” she said. “It was a flight from Amsterdam to Kuala Lumpur over European territory. There should be outrage in European capitals.”

Kramer said he expects the incident to jolt European leaders. “If this doesn’t wake the Europeans up, I don’t know what will,” he said.

Experts acknowledged the possibility that the Malaysia Airlines aircraft was brought down by Ukrainian forces or by some fluke but said the signs pointed to separatists since they reportedly shot down a Ukrainian cargo plane just a few days ago. That, and claims by a rebel leader on social media Thursday that those forces had again downed a cargo aircraft, suggest that insurgents may have brought down the highflying Amsterdam to Kuala Lumpur flight while targeting some other aircraft in the area.

“When you just sort of haphazardly fire on planes, it should not be shocking that you might hit a civilian aircraft,” said Kramer, now president of the advocacy group Freedom House. “With the approach they were taking of firing on these planes, this kind of thing was probably bound to happen.”

However, not all analysts believe the downing of the jet will be enough to change the economic calculus that has left European leaders reluctant to impose stringent sanctions on Russia.

“My prediction about the European Union is they will make loud voices but will not impose sanctions that create significant costs for themselves,” said Graham Allison, a professor at Harvard’s Kennedy School and assistant secretary of defense in the Clinton administration. “I’m betting Germany does not reduce its purchases of gas, the French don’t give back the money for the ships they’ve sold and the British don’t do anything that would disturb the City” — the London financial district where many Russian oligarchs and businesses park and trade their money.

“Unless they discover a sanction that punishes Russia without punishing Europeans — and the answer is they can’t — I think the EU is going to show its mettle,” Allison said.

In what may have been a bid to make sure Germany doesn’t endorse harsher measures in the wake of the shootdown, Putin spoke with German Chancellor Angela Merkel on Thursday. A Kremlin statement called her “a reputable European leader under whose leadership Germany has made great progress” and said the German-Russian relationship needed to be “preserved with care.” Putin also wished Merkel a happy birthday, the statement said.

Despite the pleasantries, some observers see Western countries’ relations with Russia headed into a deep freeze. “No matter which way it turns, I think it’s going to be horrible,” said Eugene Rumer, until recently a top Russia watcher for the Office of the Director of National Intelligence who now directs the Carnegie Russian Eurasia program. “It just puts Russia, politically, diplomatically in a very tough position.”

The apparent shoot-down Thursday led many to point to similar incidents in recent history, such as a 2001 episode where Ukraine’s military shot down a Russian passenger plane, the 1988 downing of an Iran Air flight by a U.S. warship, and the Soviet military’s shootdown of a Korean Air Lines flight in Asia in 1983.

Allison recalled that the KAL incident drew intense news coverage and led to a high-profile confrontation at the United Nations but little in the way of consequences for the Soviets.

“The reaction, in terms of what we did, was pretty modest,” the ex-official said.

Some of those deeply troubled by Russia’s moves in Ukraine believe the U.S. should go beyond economic sanctions and begin sending in weaponry to fortify the government in Kyiv. Schake said she’d like to see that happen, but doubts even the gruesome sight of aircraft wreckage and dead bodies strewn across the ground in Ukraine Thursday will prompt the Obama administration to go that far.

Asked how likely such a move was, she replied: “Not very.”

Edward-Isaac Dovere and Maggie Haberman contributed to this report.

CORRECTION: A previous version of this story incorrectly described Rumer’s government work.